Porphyromonas gingivalis is a gram negative anaerobic bacterium associated with advanced adult periodontitis. P. gingivalis activation of neutrophils (PMNs) even in the absence of serum factors may be associated with clinical destruction of the periodontium. Bacterial adhesion factors are known to promote attachment to human cell surfaces, P. gingivalis fimbriae may have such an adhesion factor. The overall goal of this project is to assess the interaction of P.gingivalis with human peripheral PMNs. Specifically, we will study the binding of P. gingivalis to PMNs in the absence of serum opsonization, and the effects of bacterial-PMN interactions on PMN function. Well characterized P. gingivalis strains are immobilized onto flat bottom surfaces of enzyme-linked immunosorbent assay (ELISA) plates. Normal human PMNs are then added to the plates, and after appropriate washings, binding of the PMNs to the bacteria-coated plates will be evaluated using a monoclonal Ab to PMN, and a standard ELISA technique. Alternatively, PMNs will be used to coat that plates and bacteria will be assessed for binding with anti- bacterial mAbs. We will compare fimbriated strains with non- fimbriated mutants and the effect of fimbrial protein components on specific PMN-bacteria binding. Assessment of neutrophil functions after interaction with P. gingivalis will be determined by standard functional assays such as degranulations, release of lysosomal enzymes and oxidative burst phagocytosis.